Aspirator compressor type jet propulsion apparatus



March 23 1950 H J. DE N. MccoLLuM 2,502,332

As'PIRA'roR COMPRESSOR TYPE .JET PRoPULsIoN APPARATUS Filed April 12, 1945 4 Sheets-Sheet 1 March 28, 1950 H. J. DE N. MccoLLuM 2,502,332

ASPIRATOR coMPREssoR TYPE JET PRoPULsIoN APPARATUS Filed April 12, 1945 4 sheets-sheet 2 H. J. DE N. MCCOLLUM ASPIRATOR COMPRESSOR TYPE JET PROPULSION APPARATUS March 2s, 195o Filed April 12, 1945 4 Sheets-Sheet 5 H. J. DE N. MccoLLuM 2,502,332 ASPTRATOR coMPRESSoR TYPE JET PRoPuLsIoN APPARATUS 4 Sheets-Sheet 4 March 28, 1950 Filed April 12, 1945 %NN NwYN.

Patented Mar.' 28, 1950 ASPIRATOR COMPRESSOR TYPE JET PROPULSION APPARATUS Henry J. De N. McCollum, deceased, late of Chicago, Ill., by Thehna Chicago, Ill., assignor to Stewart-Warner Corporation, Chicago, Ill., a corporation of Virginia.

Application April 12, 1945, Serial No. 587,926

(Cl. GII-35.6)

2 claims. 1

This invention relates to jet propulsion apparatus, and one object of the invention is to provide a new and improved :let engine which shall not require a mechanical air compressor for supplying air for the jet.

Another object of the invention is to provide a. jet propulsion apparatus in which auxiliary devices are driven by a separate power source so as to dispense with the provision of a gas turbine operated by the force of the jet and detracting from the total power output thereof.

It is also an object of the invention to provide a jet propulsion apparatus in which liquid fuel is preheated and vaporized in a heat exchanger adjacent' the combustion chamber, and is then discharged into the mixing tube of the apparatus at high pressure so as to aspirate and compress a sufficient quantity of air for the jet and dispense with conventional means for supplying compressed air for this purpose.

The invention also includes the provision of a jet propulsion apparatus particularly designed for use on aircraft and employing instead of a turbine operated by the jet, an aspirator compressor and an auxiliary engine adapted to operate from the same fuel supply as the jet propulsion apparatus and to drive not only the fuel pump for said apparatus but other auxiliaries required for operation of the aircraft, such as an electric current generator anda hydraulic pump- Other objects and advantages of the invention will appear from the following description taken in connection with the drawings, in which:

Fig. 1 is a side elevation partly in section and partly diagrammatic, showing a jet propulsion apparatus embodying this invention;

Fig. 2 is a vertical sectional view on an enlarged scale, showing Athe fuel' feeding nozzle withpadjacent portions of the mixing tube and air induction tube;

f Fig. 3 is a. verticaly sectional view of the pressure regulating device for the liquid fuel supply;

Fig. 4 is an enlarged detail elevation partly in section taken as indicated at line 4--4 of Fig. 1, showing the electrical igniting device;

Fig. 5 is a detail section taken as indicated at line'i-S of Fig. 1;

Fig. 6 is an axial vertical section at line 6-6 on Fig. 8, taken through the nacelle in which a McCollum, executrix,

jet propulsion apparatus embodying this invention is shown housed together with an auxiliary engine for use on aircraft;

Fig. 7 is a transverse sectional view, taken as indicated at line 1 1 on Fig. 6;

Fig. 8 is a horizontal section taken as indicated at line 8-8 on Fig. 6.

In jet propulsion devices, it is necessary to supply air for combustion under pressure, and to render the unit self-contained, a gas driven turbine has been arranged to be driven by the products of combustion for operating an air compressor. This not only absorbs a portion of the energy of the jet but frequently involves difculties arising from the high temperature of the gases fed to the turbine and the consequent danger of disintegration of the turbine wheel itself under centrifugal force at such high temperature. In the present invention, the use of a turbine and mechanical air compressor is avoided by providing for the preheating of the liquid fuel at high pressure to an extent which converts it to gaseous form at high pressure, at which it is introduced to the mixing tube of the apparatus so as to entrain or aspirate and cornpress an adequate quantity of air for combustion. Since there is no turbine in the circuit, much higher gas temperatures can be used, thus giving better efficiencies.

As shown in Fig. 1, the mixing tube I0 is of elongated tapered form, constituting a venturi with a constricted portion at I2 and with a larger entrance portion I4 having a flange I6 securely bolted to the flange I8 of an air induction tube 20. The fuel feed nozzle 22`is mounted to discharge toward the constriction I2 of the venturi and is formed as the stem portion of a- T-shaped fitting 24 shown on an enlarged scale inFig. 2. The fitting is disposed diametricallyx across the air intakepassage at the plane of junction of theflanges I 6 and I8 with the nozzle portion 22 extending at right angles from the main portion and disposed axially in the mixing tube I0. A bore 26 in the fitting 24 connects with the bore of a coupling 28 and with that 0f the feed pipe 30, and leads to the bore of the nozzle 22 for discharge of fuel into the Venturi constriction at I2. The feed pipe 30 is preferably enclosed in a heat insulating jacket 3I for reasons which will presently appear.

The air and fuel become quite thoroughly intermingled and compressed in the elongated and gradually enlarging mixing tube i8, and are delivered therefrom into a combustion chamber 32 provided with an electrical igniter 34 which may be of any suitable type as. for example, that shown in Fig. 4, having an electrically heated wire coil 36 which is mounted in a housing opening at 38 into the chamber 32 and thus exposing the heated coil 36 to the gaseous mixture in the combustion chamber. The ignited and expanding gas ows from the chamber 32 into the heat exchanger chamber 40, which is of somewhat larger diameter than the chamber 32, and which has an exhaust opening 42 at its opposite end from which the products of combustion are expelled in a powerful jet which provides the propulsive force which the apparatus is designed to generate. The particular design of the exhaust opening or jet nozzle 42 will be varied in accordance with several factors, and the form shown in Fig. 1 is merely diagrammatic.

Liquid fuel for operating the apparatus is supplied by a high pressure pump 44 which may be driven independently of the jet propulsion device, and which draws its fuel from a tank indicated at 46 and through an intake pipe 48. The feed pipe 58 extending from the pump 44 leads to ak pressure regulating device 52, one type of which is shown in detail in Fig. 3. The pipe 58 leads to a bore 54 of the device which connects with the outlet pipe 56 and is normally otherwise closed by a plunger 58 backed by a spring 68. The tension of the spring 68 may be adjusted by means of a threaded plug 62 against which the spring reacts. Whenever the pressure in the pipe 58 exceeds the predetermined value for which the spring 68 is adjusted, it will force back the plunger 58 thus admitting some of the incoming fuel to the port 64 from which a return pipe 66 leads back to the tank 4B. Any fuel which leaks past the plunger 58 will escape by way of a port 68 and return pipe 69 which also leads back to the tank 46, thus the pressure of the outgoing fuel in the pipe 56 is limited to a predetermined value and the pump will normally run at a rate sufficient to slightly exceed this pressure so as to insure the maintenance thereof.

The pipe 56 leads to a heat exchanger indicated generally by the numeral 18 and located in the chamber 48, and for purposes of illustration, this heat exchanger is shown as comprising a single continuous coil of tubing 12 connecting at its lower and upper ends into headers 14 and 16, respectively. The header 14 is tted with a cap 18 into which is secured the coupling 88 by which the pipe 56 is connected into the bore 82 of the cap 18. The inner surface of the cap 18 is recessed to form a shallow chamber 84 for the purpose to be hereinafter explained, and from this chamber the liquid fuel passes directly into the lower end of the coil 12. The upper header 16 is provided with a cap 86 which may be exactly similar to the cap 18, and into which the coupling 88 connects .the feed pipe 38 leading to the nozzle 22 in the mixing tube I8. As it passes through the coil 12 of the heat exchanger, the liquid fuel, being subjected to the intense heat of combustion in the chamber 48, is vaporized and its tendency to expand as it assumes gaseous form enormously increases its velocity in the pipe 38 so that the fuel is discharged from the nozzle 22 in gaseous form with great velocity, which serves to entrain or aspirate the air supplied through the tube 88. The decrease in velocity of the heated gas and air flowing in the mixing tube I8 builds up suiicient pressure in the combustion chamber to operate the device efliciently and to maintain a steady supply of combustible mixture which is ignited initially by the electrical igniter 34, but which will be subsequently ignited instantly upon contact with the flaming gas in the chamber 32. Therefore, if desired, the energizing current may be cut off from the igniter 34 after operation of the apparatus is under way.

Since it is necessary for the liquid fuel to be preheated and vaporized in order that it shall be discharged from the nozzle 22 with suflicient velocity to aspirate the air from the induction tube 28, the cycle can be started by providing supplemental heating means for the fuel for starting purposes. This is shown in the form of electric heating coils 98 and 92 embedded, respectively, in the cap members 18 and 86, connected together by a conductor wire 94 and connected by a wire 86 tothe feed wire 98 which extends to the igniter 34 from a battery |88 or other suitable source of electrical energy. Both the igniter circuit and the heating coils are -indicated as grounded. Thus, when the switch |82 is closed to energize the igniter, it also energizes the heating coils 98 and 92 so that as the liquid fuel supplied by the pump 44 enters the chamber 84 in the cap 18 and the similar chamber in the cap 86, it is exposed to a substantial area of heated metal by which it is rapidly voltalized and converted into gas under pressure suiiicient to operate effectively at the nozzle 22. As soon as combustion has been established, the hot gases flowing through the chamber 48 in contact with the heat exchanger 18 will serve to volatilize and preheat the fuel therein and the switch |82 can then be opened.

A propulsion unit of the type just described is well adapted for use in driving aircraft and one application for this purpose is illustrated in Figs. 6, 7, and 8. In vthese views the propulsion unit is shown housed in a shell or nacelle |84 of streamlined design. An inner shell |88 is formed at its rear end with a flange |88 secured to the inner surface of the nacelle |84. The shell |86 immediately encloses the propulsion unit which includes the elongated mixing tube ||8 having its constricted portion at ||2 and having its enlarged outer end ||4 continued outwardly in a cylindrical portion H8 and a flaring mouth ||8 forming an air intake passage designated generally b-y the numeral |28. The fuel nozzle |22 is supported in this passage by the diametrically extending portion |24 of the nozzle fitting and the outer end portionof the nozzle may be formed with a streamlined body portion |26 to reduce its air resistance. The fuel feed pipe I 38 with its heat insulating jacket |3| is connected to the nozzle fitting |24 and is accommodated mainly in the space between the nacelle |84 and the inner shell |86.

The mixing tube ||8 is of the same design as that shown in Fig. 1, and is connected to a combustion chamber |32 provided with an igniter |34 which is arranged to be electrically energized from any suitable source. The heat exchanger chamber is shown at |48 adjoining the combustion chamber |32, but at its opposite end said chamber has an elongated tapering portion |41 which terminates in an exhaust nozzle |42 through which the jet of gases constituting the products of combustion is expelled for propelling the aircraft.

The fuel pump |44 is' shown mounted on a bracket |46 secured to the upper side of the mixlng tube |I0, and the fuel inlet pipe |48 of the pump may be understood as extending from a fuel tank which may be conveniently located in the wing or fuselage of the aircraft, but which is not shown in the drawing. The pipe |50 leading from the pump |44 enters the pressure regulating device |52 which may be understood as similar in all respects to the device 52 shown in Figs. l and 3. The fuel leaves the regulator |52 by way of the pipe |56 and any excess quantity supplied by the pump is returned to the tank by pipes |66 and |69.

The heat exchanger designated generally by the numeral |10 is disposed in thechamber |40 and comprises a single coil of tubing |12 extending between headers |14 and |16 with their respective end caps |18 and |86, the pipe 56 being connected to the heat exchanger by a coupling |80, and the fuel feed pipe |30 being coupled to an elbow |88 extending from the uppercap |86. It may be understood that the caps |18 and |86 are equipped with electrical heating means |90 and |92 similar to those shown in Fig. 5 and arranged for connection with a source of electrical energy by way of conductor Wires |04, |96, of which fragments are shown in Fig. 8 the wire |94 serving to connect the two heater coils in series.

An auxiliary power plant is shown in the form of a four cylinderengne 200 of the internal combustion type mounted on the upper side of the mixing tube and connected to drive a generator 202 which will supply current by means of a conductor 203 for the airplane generally as well as for theigniter |34 and for the heating elements |90 and |92. The engineA 200 is also coupled to the fuel pump |44 for actuating it and if desired a hydraulic pump 204 may be connected to the engine 200 for supplying hydraulic pressure through conduits 205 to actuate various elements of the aircraft, such as rudders, ailerons, landing wheels, etc.

The engine 200 is shown as of the air cooled type having its cylinders provided with cooling iins and to supply cooling air the inner shell |06 is provided with an annular air intake opening 206 formed between the outwardly aring forward end of the shell |06 and the inwardly curved portion 208 of a partition 2|0 which tapers rearwardly from the inlet 206 and is joined to the mixing tube ||0. The annular throat extending from the opening 206 is thus of Venturi form in cross section with a constricted portion at 2|2 and a substantial air blast is maintained through the space in which the engine 200 is housed, particularly when the aircraft is in motion. The air flowing through this space and carrying away this waste heat of the engine 200 movesrearwardly through an annular space formedv between the shell |06 and an inner shield 2 4 which is of the same general contour as the combus-l tion chamber |40 and its tapering portion |4|, and is mounted in spaced relation thereto as shown in Figs. 6 and 8. A portion of the air within the shell ows rearwardly through the space between the shield 2|4 and the wall of the chamber |40, so that the two rearwardly moving annular streams of air emerge from the rear end of the nacelle through annular outlets 2|6 220 and if desired it may lead from the same tank as that from which fuel is drawn by the pump |44 for the jet propulsion apparatus. The exhaust pipe of the engine is shown at 222 discharging into the space between` the shield 2 I4 and the chamber |40. vBefore the jet propulsion apparatus can be placed in operation, its fuel must be heated; therefore, the first step is to start the engine 200 whereupon the generator 202 will supply current forthe heating elements |90 and |92 and the pump |44 will commence to feed liquid fuel through the heat exchanger |10. The operation of the engine 200 and the generator 202 l, will also provide electrical energy for the igniter |34 so that the first mixture of fuel with air owing from the mixing tube I I0 into the combustion chamber |32 will be ignited and combustion will proceed through the chamber |40. Thereupon, the heat exchanger |10 will assume the function of vaporizing and preheating the fuel so that the current supplied to the electrical heaters |90 and |92 may be switched off if desired and combustion will continue to maintain itself without aid from the electrical igniter |34. The engine 200 will continue to operate, however, for performing` auxiliary functions in connection with the aircraft, as well as Ifor driving the fuel pump. l

While there is shown and described herein certain structure illustrating the invention, it is to be understood that the invention is not limited thereto or thereby but may assume numerous l other forms, and includes all modifications, variations. and equivalents coming within the scope of the following claims:

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In combination with a jet propulsion apparatus, a streamlined nacelle for housing the same having an air intake opening at its front end, said apparatus including an elongated mixing tube extending from said opening, means v arranged to fed liquid fuel to said heat exchanger and 2|8 serving to cool the chamber |40 and the under pressure, and a conduit for the fuel, va`

porized in the heat exchanger leading therefrom to the fuel nozzle in the mixing tube, together with an engine housed in the nacelle, a generator driven thereby for energizing the igniting means and a drive connection from said engine to the fuel pump, said nacelle having an additional air intake opening of annular form surrounding the aforesaid air intake and an annular air outlet at the rear end surrounding the jet outlet to provide a stream of air through the nacelle for cooling the mechanism in said nacelle.

2. In combination with a jet propulsion apparatus, a streamlined structure for housing the same having an air intake opening at its front end, said apparatus including an elongated mixing tube extending from said opening, means forming a combustion chamber having said mixing tube connected thereto at one end and tapering at its opposite end to a jet outlet in the rear end of said structure, a fuel nozzle discharging into the mixing tube to aspirate air from said ture, and a drive connection from said engine 10 to the fuel pump, said structure having an additional air intake opening adjacent the front end of said structure and an air outlet opening at the rear oisaid structure to provide a stream of air through said structure for cooling the mechanism therein.

. THELMA McCOLLUM,

Emecutria: of the Last Will and Testament of Henry J. De N. McCollum, Deceased.

. 8 REFERENCES CITED The following references areof record in the le of this patent:

UNrIED STATES PATENTS Number Number Name Date Goddard July 14, 1914 Bostedo Feb. 7, 1922 Adams Mar. 16, 1937 Hammers et a1. Mar. 8, 1938 Whittle July 16, 1946 FOREHGN PATENTS Country Date France Dec. 23, 1920 France Feb. 5, 1934 

